This invention relates to sulfonated perfluorovinyl monomer compositions, methods for making same, and polymers made from them.
Perfluorinated allyl vinyl ethers have been described, for example in U.S. Pat. No. 4,337,211 that describes alkyl fluorocarbon ethers and methods for preparation thereof, and U.S. Pat. No. 4,358,412 that describes methods for preparation of alkyl vinyl ether monomers.
U.S. Pat. No. 5,264,508 describes polymers and copolymers prepared from diunsaturated mono-or poly-perfluoro or haloperfluoro ethers. One site of unsaturation is used in the polymerization, resulting in a melt-processable polymer. The second site of unsaturation is then available to crosslink the polymer giving a thermoset polymer. The copolymerization monomers said to be useful include xe2x80x9cvirtually any ethylenically unsaturated monomer capable of polymerization.xe2x80x9d (col. 5 lines 31-32). Phenyl and naphthyl radicals may be included in an ether used in the copolymerization, and these radicals may include substituent groups such as a halogen or xe2x80x94SO2F.
U.S. Pat. No. 5,449,825 describes a method of preparation of perfluoro and haloperfluoro ethers, diethers and polyethers containing vinyl unsaturation, or allyl and vinyl unsaturation.
U.S. Pat. No. 5,023,380 describes compounds having two or more perfluorovinyl groups, along with their polymerization. Sulfur and sulfur-containing groups may be in the backbone of these materials. A hydrocarbyl group in the backbone must be either unsubstituted or inertly substituted, which is said to include sulfide, sulfoxide, and sulfone.
U.S. Pat. No. 5,066,746 describes a process of preparing tris-perfluorovinylether monomers.
WO 99/38842 describes perfluorovinylbenzene sulfonyl fluoride as a precursor to a polymer. It also describes polyimide-type aromatic polymers of sulfonated sulfone polyethers, and mono-and bi-functional monomers that can have sulfur-containing backbones or substituents.
WO 97/25369 describes several composite membranes that include various trifluorostyrene, substituted trifluorostyrene, and ethylene-based monomers.
WO 99/05126 describes perfluorovinyl ionic compounds and polymers made using them. The formulas described include perfluorovinyloxy substituents on a pentacyclic group and a backbone containing an aromatic group having one or more substitutents in addition to a sulfonyl group.
The polymerization of trifluorovinyl-containing monomers to form perfluorocyclobutylene polymers has been disclosed. For example, U.S. Pat. Nos. 5,037,917 and 5,066,746 describe a thermal process for preparing a polymer containing perfluorocyclobutane rings. The typical monomers described in these references have at least two dimerizable perfluorovinyl groups.
Briefly, the present invention provides a monomer having the formula A-B, wherein A is represented by Formula I: 
wherein B is selected from xe2x80x94OCFxe2x95x90CF2 and xe2x80x94A; wherein, when B is OCFxe2x95x90CF2, the orientation of B is meta or para to the trifluorovinyloxy group of A; wherein, when B is A, the bond joining the A groups is para to the trifluorovinyloxy group of each A; and wherein each Z is independently selected from xe2x80x94SO2F, xe2x80x94SO2Cl, xe2x80x94SO3H, xe2x80x94SO2xe2x80x94N(M)xe2x80x94SO2CF3, and xe2x80x94SO2xe2x80x94N(M)xe2x80x94SO2Rf; wherein M is any suitable cation and Rf is a C1 to C10 fluorocarbon or fluorinated ether group.
The present invention also provides a monomer according to Formula II: 
wherein X is F, Cl, or N(M)SO2Rf, wherein M is any suitable cation and Rf is a C1 to C10 fluorocarbon or fluorinated ether group.
In this document xe2x80x9csubstitutedxe2x80x9d when used without reference to a particular substituent, means substituted by conventional substituents which do not interfere with the desired product or process, e.g., substituents can be alkyl, alkoxy, aryl, phenyl, halo (F, Cl, Br, I), cyano, nitro, etc. Also, xe2x80x9cC(number)xe2x80x9d refers to a chemical moiety containing the indicated number of carbon atoms.
These monomers are useful in preparing polymers such as described in copending U.S. patent application 09/587,522. Such polymers can have desirable mechanical properties along with a desirable level of ionic conductivity. For example, block copolymers have sulfonated and non-sulfonated blocks can be prepared. By controlling the block proportions of sulfonated monomer, the ionic conductivity of the resultant polymer can be controlled. By controlling the block proportions of one or more other monomers, the mechanical properties of the resultant polymers can be controlled.
The present invention provides perfluorovinyl monomers comprising sulfonated units and methods for making them. The present invention also provides polymers comprising the monomers having sulfonated units. These monomers have at least two trifluorovinyloxy groups that are attached to one or more aryl groups. 
The general form of the monomers of the present invention is A-B. The first portion, A, is represented by Formula I, shown above, with an open valence to a B group. Thus, A includes a core aryl group with a trifluorovinyloxy group and a separate group defined by Z.
B is either xe2x80x94OCF=CF2, or a second A group. When B is a second trifluorovinyloxy group, the core aryl group has two trifluorovinyloxy substituents that are either meta or para to each other. When B is a second A group, the trifluorovinyloxy group of each A group is para to the bond connecting the two A groups.
Z is independently selected from sulfur-containing subgroups, for example, xe2x80x94SO2F, xe2x80x94SO2Cl, xe2x80x94SO3H, xe2x80x94SO2xe2x80x94N(M)xe2x80x94SO2CF3, and xe2x80x94S02xe2x80x94N(M)xe2x80x94SO2Rf, wherein M is any suitable cation and Rf is a C1 to C10 flurorocarbon or fluorinated ether group. The choice of which particular group for each Z and the orientation of each Z group are independently selected. Generally, Z is ortho or meta to the xe2x80x94OCFxe2x95x90CF2 group of portion A.
M is any suitable cation, such that it does not interfere with polymerization and that it is exchangeable with other cations, particularly H+. Examples include H+, alkali metals, and R4N+ where R4 is a C1-C10 saturated alkyl group.
Rf can be any suitable C1 to C10 fluorocarbon or fluorinated ether group. Examples include fluorocarbons having the formula CnF2n+1 wherein n is an integer from 1 through 10. Examples of fluorinated ether groups include CF3(CF2)yOCF2CF2xe2x80x94, wherein y is an integer from 1 through 7, and Rkxe2x80x94CH2OCF2CF2xe2x80x94, wherein Rk is CF3 or CmF2m+1 with m being an integer from 1 through 7.
Another monomer of the present invention comprises a reaction product of a tris(trifluorovinyloxy aryl) alkane, such as 1,1,1-tris(4xe2x80x2-trifluorovinyloxyphenyl)ethane, and a sulfonated trifluorovinyloxyaryl monomer.
Any suitable reaction conditions and equipment may be used to prepare the monomers of the present invention, including batch or continuous processes. Suitable conditions and equipment disclosed in the examples section below may be used. Generally, a base material having the target phenyl groups is reacted to replace the hydrogen on the substituent phenyls with an alkali metal. Then a halo-tetrafluoro alkane is substituted for the alkali metal. The halotetrafluoroalkane-substituted intermediate is then sulfonated, such as with a halosulfonic acid, This reaction product is neutralized, dried, and purified. Then the material is fluorinated by substituting fluorine for the halo in the halosulfonic acid substituent. Finally, a dehalogenation process converts the halotetrafluoroalkane substituent to the desired trifluorovinyloxy group.
The monomers of the present invention may be polymerized by any suitable method. Polymerization involves joining trifluorovinyl groups of the monomer molecules to form linking perfluorocyclobutylene (PFCB) groups. In addition, the monomers of the present invention may be copolymerized with any suitable co-monomer or co-monomers. Heating is a preferred method of polymerization of the monomers or monomer mixtures.
Desirable properties may be obtained by controlling the relative amounts of the sulfonated monomer or monomers and non-sulfonated monomers. Higher quantities of sulfonated monomer tend to result in higher ionic conductivity in the resultant polymer, at the expense of lower mechanical properties. By including non-sulfonated monomers, such as di(trifluorovinyloxy)aromatic monomers, CF2xe2x95x90CFOxe2x80x94Phxe2x80x94OCFCxe2x95x90F2, (CF2xe2x95x90CFOxe2x80x94Phxe2x80x94)2, and 1,1,1-tris(4xe2x80x2-trifluorovinyloxyphenyl)ethane, the electrical and mechanical properties of the polymer can be targeted for a particular use. These monomers are therefore useful in preparing polymers having properties desirable for ion-exchange membranes.
The versions of the invention described above have many advantages, including controlled mechanical and electrical properties.